1. Field of the Invention
The present invention relates to an agricultural cutting machine intended to be moved in a direction of work and comprising:
a chassis, PA1 a harvesting mechanism intended to rest on the ground during work and equipped with cutting members, the harvesting mechanism having a center of mass, PA1 a suspension device connecting the said harvesting mechanism to the chassis and comprising a lower suspension member and an upper suspension member forming an articulated quadrilateral which allows the harvesting mechanism to move relative to the chassis, the lower suspension member and the upper suspension member each being connected to the chassis by means of a first respective articulation and to the harvesting mechanism by means of a second respective articulation, the first articulations and the second articulations each having a geometric axis which is substantially horizontal and transverse to the direction of work. PA1 a chassis running along the ground, PA1 a harvesting mechanism equipped with a cutter bar which has cutting sections, with a reel and with a windrowing screw, and PA1 a suspension device connecting the harvesting mechanism to the chassis and comprising two lower suspension links and an upper suspension link forming an articulated quadrilateral which allows the harvesting mechanism to move relative to the chassis. PA1 for the lower suspension member to comprise two lower suspension links each one extending near a respective longitudinal end of the harvesting mechanism, and PA1 for the upper suspension member to consist of an upper suspension link.
2. Discussion of the Background
An agricultural cutting machine of this kind is described in document U.S. Pat. No. 4,473,993. This machine comprises:
The two lower suspension links are each connected to the chassis by means of a first respective articulation and to the harvesting mechanism by means of a second respective articulation. Furthermore, they each extend close to a respective longitudinal end of the harvesting mechanism.
The upper suspension link is also connected to the chassis by means of a first articulation and to the harvesting mechanism by means of a second articulation. This upper suspension link extends, when viewed from above, in the central part of the chassis and of the harvesting mechanism. Moreover, it is produced in the form of a hydraulic ram so that the cutting angle of the cutter bar can be adjusted.
This hydraulic ram is a single-acting ram. For this purpose, the second articulations of the two lower suspension links are arranged in such a way that an increase in cutting angle is brought about by the weight of the harvesting mechanism, while a decrease in the cutting angle is achieved using the ram.
For the weight of the harvesting mechanism actually to be capable of bringing about the correct increase in cutting angle, the center of mass of the harvesting mechanism needs to lie an appropriate distance forward of the second articulations of the two lower suspension links.
This means, particularly during transport, that the upper suspension link transmits not insignificant forces to the chassis, which forces may cause mechanical failures. In seeking to strengthen the various components to make them capable of withstanding these forces, there is a risk that the weight of the machine will be substantially increased.
During work, this layout may lead to a lack of stability of the cutting mechanism which is also detrimental to the good mechanical robustness of the various components and may have a harmful influence on the quality of work done. This phenomenon is felt all the more as the forward speeds increase.